<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>属性选择器</title>
</head>
<body>
<input type="text">
<input type="password">
<input type="password">
</body>
<script src="js/jquery-3.3.1.min.js"></script>
<script>
    let in1 = $("input[type]")
    alert("属性名选择器"+in1.length)

    let in2 = $("input[type='password']");
    alert("属性值选择器"+in2.length)
</script>

</html>